The highest frequency of landslides is occurring in the
area consisting of shale intercalated with sandstone.
Bedding planes between shale and sandstone horizons,
fractures and fissility in rocks mass act as weak zones
which allow high infiltration of rain water. These weak
zones cause the rocks to be subjected to high weathering,
and high to slope failures. The dip of bedding plane of
the study area varying from 30 to 50 degrees, toward to
the valley floor can also accelerate the slope failures.
Field evidences showing vegetation cover do not have
much resistance for sliding process in this area. Because
of the area affected by sliding is mostly covered by
moderate to dense vegetation. Extensive human activities
in the form of agricultural activities and road excavations
have also influenced the slope instability phenomena.